1. Technical Field
The present invention relates to an optical touch panel apparatus optically performing position detection and to a recording medium.
2. Description of Related Art
One of the conventionally-used touch panel apparatus is an optical touch panel apparatus. Japanese Patent Application Laid-Open No. 2002-91683 discloses an example of the optical touch panel apparatus. The optical touch panel apparatus includes a plurality of light emitting elements arranged in the x-axis direction and the y-axis direction along the side of a rectangular flat panel, and a plurality of light receiving elements at positions opposed to the light emitting elements along the side of the flat panel. The light emitted by a light emitting element moves along the surface of the flat panel and is received by a light receiving element. Accordingly, an optical path in which the light emitting element emits light and the light receiving element receives light is formed on the flat panel. When a user places a light blocking object such as a finger or a pen on the flat panel, a light receiving element which cannot receive light occurs due to the light blocking object blocking light. The optical touch panel apparatus identifies a position of a light receiving element which cannot receive light among the light receiving elements arranged in the x-axis direction and the y-axis direction, to detect a position of the light blocking object on the flat panel.
The light emitting elements and the light receiving elements in the optical touch panel apparatus are so arranged that each light emitting element is opposed to each light receiving element in one-to-one correspondence. As for the method of detecting a position of a light blocking object performed by the optical touch panel apparatus, there are a whole area scanning method scanning the entire flat panel and a specific area scanning method scanning while focusing around the light blocking object. In the whole area scanning method, the optical touch panel apparatus causes a plurality of light emitting elements, from one end to the other end, to sequentially emit light, and causes a plurality of light receiving elements, each of which is opposed to each of the light emitting elements in one-to-one correspondence, to receive the light. The light from one light emitting element is received by one light receiving element. Optical paths of the light received by a plurality of light receiving elements that are in one axial direction are in parallel with one another. The resolution for position detection is determined by a distance between adjacent light emitting elements.
In the specific area scanning method, the optical touch panel apparatus causes a plurality of light receiving elements to receive light from one light emitting element. The optical paths of light received by the plurality of light receiving elements are radial optical paths starting from one light emitting element. Due to increased density of the optical path used for position detection, the resolution for position detection is more enhanced in the specific area scanning method than the whole area scanning method. The optical touch panel apparatus first roughly detects the position of a light blocking object by the whole area scanning method to detect the light blocking object, and then scans an area around the light blocking object with the specific area scanning method, to detect the position of the light blocking object with high accuracy.